1) Field of the Invention
This invention relates to a method for the purification of tissue plasminogen activator (tPA), and more specifically to a method for purifying tPA from a crude tPA preparation, which contains various tPA species of different molecular weights and other proteinaceous impurities, by bringing the crude tPA preparation into contact with hydroxyapatite and then separately isolating and purifying tPA species of different molecular weights with eluents, whose pHs and/or salt concentrations have been adjusted in advance, and to which one or more additives may be added if required.
2) Description of the Prior Art
Use of hydroxyapatite for the purification of tPA has itself been known. In a method using hydroxyapatite, in order to obtain tPA from a crude tPA preparation, tPA is adsorbed to the hydroxyapatite, and thereafter eluted from the tPA-bearing hydroxyapatite with ammonia-containing solution (see Japanese Patent Laid-Open No. 76419/1986 for instance). Under conditions employed for the above elution, tPA species of different molecular weights could not be separated from one another and moreover, the activity of tPA might be reduced.